Method of preventing distortion in butt-welded plates



Sept. '14, 1948. L. P. MccABE 2,449,082

IBIHOD 0F PREV ENTING DIST ION BUT ELDED PLA led ril 5, l

A Tree 1v: Y

Patented Sept. 14, 1948 METHOD OF PREVENTING DISTOBTION IN BUTT-WELDEDPLATES Louis r. McCabe, minis, N. Y.

Application April 5, 1946, Serial No. 859,740

(Granted under the act of March a, 188:, as amended. April :0, 1928; o.o. m)

4 Claims.

This invention relates to a method for welding and more particularly toa method for preventing the distortion of welded plates at the weldedarea.

A particularly objectionable feature of multiple-pass welding of angledjoints is the distortion that takes place at the welded area. When tworelatively large and thick plates such as may be used in theconstruction of decks of ships, bridges, driveways, etc., are to beJoined, the most common method of joining the plates is to make singlegroove welds by multiple passes. This method comprises making athickness of weld near the root or base of the two plates, then whenthis'first layer of weld has cooled, making another pass or weld atop ofthe initial weld.

As the weld is built up in this manner, the passes or layers of weldcontract, tending to compress the top opposing faces of the thick platestowards each other. After each pass has been completed for a particularweld, the compression becomes greater, so that the buckling ordistortion that occurs is beyond a tolerable range, resulting indeviations as high as from a horizontal plane.

To compensate for this root shrinkage and consequent distortion of theupper faces of the plates being welded, strongbacks were used topredistort the plates in a direction opposite to their normaldistortiontendency during multiplepass welding with the hope that thecontracting force of the weld would return the predistorted plates to aposition wherein the top faces of the welded plates would be in ahorizontal plane. More often than not, it was extremely difficult togauge the amount of predistortion to apply to the plates that were to bewelded. Moreover, some types of joints preclude counter distortionbecause of backing or supporting structure contiguous with the plates.

The more feasible method relies on the use of wedges to counteract thecompressive forces of multiple-pass welds. This invention treats of theuse of wedges, but in a novel manner, so as to eliminate theaforementioned undesirable distortion. Hence, the principal object ofthis invention is to provide a novel method for preventing distortion ofwelded plates during the welding process.

Further objects and advantages of this invention, as well asconstruction, arrangement and operation thereunder, will be apparentfrom the following description and claims in connection with theaccompanying drawing,,in which,

Figure 1 is a-plan view of apparatus employed to perform the method thatconstitutes the present invention,

Figure 2 is a view taken of Figure 1, and

Figure 3 is a view taken along the line 3-3 of Figure 1.

Figure 1 shows a pair of plates III that are spaced apart and resting ona plate ll. Bevels I! are cut into the plates l0 and subtend an angle Xas shown in Figure 2. This angle varies with each weld and usually liesbetween 15 and 45. It was customary, prior to the method to along theline 2-2 be described herein, to place a wedge between the plates in sothat the walls of the wedge were flush with the walls of the bevels l2.When the space S was filled with a suitable welding compound, thecompression forces against the wedge walls were so great that the wedgehad to be burned out of its seat between the plates ill or otherwisedestroyed in its removal from the space S.

The novel method suggested in the present application provides for awedge whose subtended angle 0 is three to five degrees greater thanangle X. In inserting such a wedge [3 between the plates III, thecompression forces of the plates III are applied to the wedge I3 along aline on each side of the wedge l3, rather than along .the broad surfacesof the wedge l3, as would occur when the latter .is cut an angle suchthat angle 0 equals angle X.

The angle bar I 4 is welded to both plates ID to form an overhead bridgeover the wedge l3 so that another wedge l5 can be inserted betweensaddle of bar I4 and the butt of wedge i3, thus preventing the wedge l3from springing out of its position between the plates in. After the weldon both sides of the wedge 13 has been completed, the wedge I5 isknocked out, the angle bar I4 is fused off or otherwise removed from theplates I0, and the wedge 13 is pried and/or knocked out of its position,the wedge l3 being available for use for another welding operation onbeveled plates such as plates l0.

While it is known that the use of mechanical spacers to restraincompressive forces is old, the use of wedges whose subtended angle isless by a predetermined amount than the angle subtended by the facingbevels of plates that are to be welded by the multiple-pass method isdeemed novel and results in a more expeditious welding operation, adistortion-free weld, and also permits of the preservation of the wedgeafter the completion of the welding operation.

It is understood that various modifications and wedge against said 3changes may be made in this invention without departing from the spiritand scope thereof as set forth in the appended claims.

The invention described herein meg he meow factured and used by or forthe Gloveent oi? the United States of Americas for goveentsl purposeswithout the payment of any royalties thereon or therefor.

What is claimed is: V

i. A method for preventing distortion of plates during the weldingthereof opts the steps of bevelling the facing surifnces to he welded sothat said surfaces subtend e predetermined angle, and prior to thewelding process,

feces, sold wedge subtendlng an angle greater than the angle subtendedby the bevelled surfaces.

2. A method for prevent it. during the welding thereof comprising; thestem of bevelling the fee surteees to he welded so that said surfacessubtend s predetermined angle, and prior to the wel process. interposingagainst said faces a. wedge whose subtended angle is greater than theangle subtended hr the bevelled surfaces, and applying a. constant forceagainst the butt of the wedge during the welding process.

3. A method for preventing distortion of pistes during the weldingthereof oomprising the steps of bevelling the iecing silrfinces to heinter-mains s.

distortion of plates welded so Iih lid

that said surfaces slibted an angle between 15 and 45, and prior to thewelding process. interposins against said opposing bevelled loses awedge whose subtended angle is greater by 3 to 5 than the anglesubtended by the bevelled surfacesend applying a constant force againstthe butt of the wedge during the welding process.

4. A method for preventing distortion of plates during the weldingthereof comprising the steps of hevelllng the facing surfaces to bewelded so that said surfaces subtend an angle between 15 and 45, andprior to the welding process, interposins against said opposing bevelledfaces a wedge whose subtended angle is greater by 3 to 5 than the anglesubtended by the bevelled i'eces so that the interposed wedge shutssubstantially I along a line of each bevelled surface rather then overits entire bevelled surface, and applying s. constant force against thebutt of the wedge during the welding process.

. LQ'UIS P. MOCABE.

nnennmsons ot'rnn The following references are of record in the

